Faculty Publications
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Publications by NITK Faculty
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Item Online structural health monitoring of pretwisted anisotropic beams(DEStech Publications, 2007) Harursampath, D.; Harish, A.B.; Kiran, S.Delamination is a mode of damage in laminated composites, which might occur either during manufacturing or during service in regions of material and geometric discontinuity. An effective and efficient mathematical model has been developed to assess the degradation in stiffness properties of a pretwisted anisotropic strip due to delamination. The same is implemented using MATLAB to enable Online Structural Health Monitoring. This model captures the non-linear effects in a strip thai arise due to thin & slender geometry in the presence of delamination at generic locations and can be used for static & dynamic applications. The possible direct application of this model is to helicopter flexbeams, and keeping this in view, a strip made of antisymmetric layup composed of symmetric sublaminates with a small pretwist is considered in the formulation. Variational Asymptotic Method (VAM) is used as a mathematical tool to systematically disintegrate the original geometrically nonlinear 3D problem and the sublaminate approach further simplifies the formulation. This is demonstrated by considering a strip made of piezoelectric fibre composites subjected to an axial load, typically caused by a centrifugal force on a helicopter rotor flexbeam. The model developed is not limited in application as the type of delamination and layup considered is generalised and hence offers critical insight. Also considered is the random nature of material properties. This work provides an effective mathematical tool for Online Structural Health Monitoring of pretwisted anisotropic beams due to delamination. © © 2007 by DEStech Publications, Inc. All Rights Reserved.Item Coupled evaluation of the free vibration characteristics of magneto-electro-elastic skew plates in hygrothermal environment(Techno-Press, 2019) Mahesh, V.; Kattimani, S.; Harursampath, D.; Nguyen, N.-T.The present article addresses the coupled free vibration problem of skew magneto-electro-elastic plates (SMEE) considering the temperature-moisture dependent material properties. The plate kinematics follows Reddy?s higher order shear deformation theory. With the aid of finite element methods, the governing equations of motion are derived considering the Hamilton?s principle and solved by adopting condensation technique. The influence of different temperature and moisture dependent empirical constants on the frequency response of SMEE plate has been assessed. In addition, the natural frequencies corresponding to various fields are evaluated and the effect of empirical constants on these coupled frequencies is determined. A detailed parametric study has been carried out to assess the individual effects of temperature and moisture dependent empirical constants along with their combined effect, aspect ratio, length-to-width ratio, stacking sequence and boundary conditions. The results reveal that the external environment as well as the geometrical skewness has a significant influence on the stiffness of the SMEE plates. © 2019 Techno-Press, Ltd.Item Thermal response analysis of multi-layered magneto-electro-thermo-elastic plates using higher order shear deformation theory(Techno-Press, 2020) Mahesh, M.; Harursampath, D.; Kattimani, S.C.In this article, the static responses of layered magneto-electro-thermo-elastic (METE) plates in thermal environment have been investigated through FE methods. By using Reddy’s third order shear deformation theory (TSDT) in association with the Hamilton’s principle, the direct and derived quantities of the coupled system have been obtained. The coupled governing equations of METE plates have been derived through condensation technique. Three layered METE plates composed of piezoelectric and piezomagnetic phases are considered for evaluation. For investigating the correctness and accuracy, the results in this article are validated with previous researches. In addition, a special attention has been paid to evaluate the influence of different electro-magnetic boundary conditions and pyrocoupling on the coupled response of METE plates. Finally, the influence of stacking sequences, magnitude of temperature load and aspect ratio on the coupled static response of METE plates are investigated in detail. © © 2020 Techno-Press, Ltd.Item On vibration analysis of functionally graded carbon nanotube reinforced magneto-electro-elastic plates with different electro-magnetic conditions using higher order finite element methods(China Ordnance Industry Corporation, 2021) Mahesh, M.; Harursampath, D.; Kattimani, S.This article deals with evaluating the frequency response of functionally graded carbon nanotube reinforced magneto-electro-elastic (FG-CNTMEE) plates subjected to open and closed electro-magnetic circuit conditions. In this regard finite element formulation has been derived. The plate kinematics adjudged via higher order shear deformation theory (HSDT) is considered for evaluation. The equations of motion are obtained with the help of Hamilton's principle and solved using condensation technique. It is found that the convergence and accuracy of the present FE formulation is very good to address the vibration problem of FG-CNTMEE plate. For the first time, frequency response analysis of FG-CNTMEE plates considering the effect of various circuit conditions associated with parameters such as CNT distributions, volume fraction, skew angle, aspect ratio, length-to-thickness ratio and coupling fields has been carried out. The results of this article can serve as benchmark for future development and analysis of smart structures. © 2020 The AuthorsItem Development of Sustainable Jute/Epoxy Composite and Assessing the Effect of Rubber Crumb on Low Velocity Impact Response(Taylor and Francis Ltd., 2022) Mahesh, V.; Mahesh, V.; Harursampath, D.; Joladarashi, S.; Kulkarni, S.M.In the current study, the experimental assessment of influence of rubber crumb on the low velocity impact (LVI) behavior of jute epoxy composites are carried out using two types of impactors namely hemispherical and conical. Hand layup technique is used to fabricate the proposed composites. The rubber crumb is incorporated in the epoxy resin with 1.5 wt%, 3 wt%, and 5 wt%. Results revealed that incorporation of 3 wt% of rubber crumb resulted in better LVI response compared to its counterparts. Fractography studies revealed that inclusion of rubber crumb particles enhances the adhesion between resin and fiber, thereby increasing the energy absorption. In addition, they aid in reducing damage area and increasing penetration threshold of proposed composites. The current study’s systematic technique serves as a model for the efficient use and conversion of waste rubber crumb into usable natural fiber reinforced polymer matrix composites for LVI applications. © 2022 Taylor & Francis.Item Experimental investigation of the in-plane quasi-static mechanical behaviour of additively-manufactured polyethylene terephthalate/organically modified montmorillonite nanoclay composite auxetic structures(SAGE Publications Ltd, 2023) Mahesh, V.; Maladkar, P.G.; Sadaram, G.S.S.; Joseph, A.; Mahesh, V.; Harursampath, D.Apart from the inherent anomalous behaviour under tensile and compressive structures, auxetic structures have shown improved energy absorption characteristics that are of prime interest to various fields of study. This is further exemplified by additive manufacturing (AM) techniques and polymer composites to tailor the shape, geometry and form of these structures. Consequently, this paper aims to characterise the in-plane compressive behaviour and negative Poisson’s ratio (NPR) of the most prominent auxetic structures fabricated additively used polymer nanocomposite materials. The study incorporates the use of glycol-modified polyethylene terephthalate (PETG) and nanocomposites of PETG filled with organically modified montmorillonite (OMMT) nanoclay particles to produce auxetic structures fabricated through fused filament fabrication (FFF). Different structures such as hexagonal re-entrant honeycomb structures, peanut-shaped honeycombs, chiral honeycomb structures and missing rib structures are characterised for their compressive performance through experimental approaches involving mechanical testing and digital image correlation (DIC). Different parameters such as the peak crushing strength, average crushing strength, NPR, specific energy absorption (SEA), and crush force efficiency (CFE) of these structures are evaluated at different strain rates/loading rates for varying concentrations of nanoclay and PETG. It is observed that higher loadings of nanoclay particles lower the compressive strength of the structures. Additionally, the NPR decreases with increasing strain rates and is also influenced by the composition and the resultant stiffness. Moreover, the geometrical parameters of the structure largely influence its strain energy absorption. The results have shown that such material-structure combinations can produce structures of high-performance capabilities suitable for aerospace applications. © The Author(s) 2022.Item Tribological performance and 3-D surface characterisation of age-hardened Al2090-based ceramic composites(SAGE Publications Ltd, 2025) Sharath, B.N.; Mahesh, V.; Mahesh, V.; Kattimani, S.; Harursampath, D.This study investigates the synergistic influence of boron nitride (BN) tertiary ceramic additives and age-hardening treatment on the microhardness and wear resistance of Al2090-based hybrid composites, fabricated using the stir casting method. X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM) studies are carried out to assess the phases present, microstructure, and surface properties, respectively. The metallurgical investigations confirm a relatively superior uniformity in the distribution of particles and the ageing of precipitation at 150°C, vis-à-vis the other temperatures explored in this study. The experimental examinations conducted as per ASTM (E8 and G99) standards revealed a significant improvement in both the hardness and the primary tribological properties, when micron-sized boron carbide, graphite, and boron nitride were used as reinforcements. Age-hardened samples, especially the hybrid composite HS-2 with 5 wt.% each of boron carbide, graphite, and boron nitride, demonstrated an enhanced hardness of 25.23% and lower surface roughness (44.3 nm) compared to Al2090 (AS), due to the presence of load-bearing ceramic reinforcements. Increasing the applied load led to higher wear rates and coefficients of friction for Al2090. However, heat-treated hybrid metal matrix composites (HMMCs) exhibited a contrary behaviour, suggesting enhanced durability. The investigation highlighted the better wear resistance of heat-treated and near-optimally reinforced HMMCs, indicating their potential candidature for wear-resistant aerospace applications. © IMechE 2025.Item Machine learning enhanced multi-scale dynamic viscoelastic analysis of 3-D printable PETG nanocomposite filaments: Leveraging FFT-based mesh-free computational homogenization for complex microstructures(Elsevier B.V., 2025) Aher, Y.; Mahesh, V.; Joseph, A.; Mahesh, V.; Kattimani, S.; Harursampath, D.The article investigates the influence of organically modified montmorillonite nanoclay (OMMT-NC) and short carbon fibers (SCF) on temperature-dependent mechanical properties of additively manufactured glycol-modified polyethylene terephthalate (PETG) nanocomposites. This work utilizes Dynamic Mechanical Analysis (DMA) to explore the influence of microstructure on the multiscale viscoelastic properties and the resulting stiffness-damping trade-off in porous nanocomposites. Machine learning (ML) and X-ray Micro-Computed Tomography (micro-CT) are employed to bridge the gap between experimental measurements from DMA and computational modelling. A novel mesh-free computational approach, combining fast Fourier transform (FFT)-based homogenization and the Lippmann-Schwinger (LS) method, was applied to analyze the porous heterogeneous microstructures. The analysis of pore geometry and fiber distribution, along with the associated stress-strain behavior, provides valuable information regarding stress concentration at critical material interfaces. The proposed method revealed a higher Von Mises stress and strain in the matrix surrounding the fiber ends, a principal locus of load transmission. Further, the experimental DMA results highlight the importance of considering interfacial adhesion, friction, segmental mobility, and intercalation effects on modulus, Tg, and tan ?. PETG +15 wt % SCF demonstrated high damping (tan ?: 0.19) and a 35 % and 122 % rise in modulus in glassy and rubbery states, respectively. Meanwhile the relative modulus of PETG +1 wt % OMMT-NC + 5 wt % SCF and PETG +3 wt % OMMT-NC + 5 wt % SCF nanocomposites improved by over 41 % in the glassy state. © 2025 Elsevier B.V.Item On enhancing the high-temperature wear behaviour of Al2090-based hybrid composites using tertiary ceramic particles(SAGE Publications Ltd, 2025) Sharath, B.N.; Mahesh, V.; Mahesh, V.; Kattimani, S.; Harursampath, D.This study explores the impact of reinforcing an Al2090 matrix with silicon nitride (Si3N4) as a tertiary ceramic alongside boron carbide (B4C) and graphite (Gr) to improve wear resistance at elevated temperatures. Hybrid composite samples were produced using the stir-casting technique. Experimental results show that incorporating Si3N4increased hardness by 35.7%, while wear resistance improved by 43.7% with a combined reinforcement of B4C, Gr, and Si3N4at 18 wt.%. Scanning electron microscopy (SEM) revealed the formation of a mechanically mixed layer (MML) composed of B4C, Gr, and Si3N4, which acted as an effective insulating barrier, protecting the sample surface from the steel disc. A noteworthy 69% of wear resistance improvement was accomplished at 300 °C for the composite with 9 wt.% B4C, 6 wt.% Gr, and 3 wt.% Si3N4. Atomic force microscopy (AFM) analysis further indicated enhanced surface properties for this composition. These findings highlight the potential of this hybrid composite for high-temperature aerospace applications, such as in engines, heat shields, and structural components. © IMechE 2024